There's lots of royalty free graphics and sounds
on the web which you can freely use in your games. here's a list over the sites I use.
Ari Feldman's Spritelib The classic. Great GFX for your very first game!
Reiner's Tilesets Bigger and more advanced sprites and tiles.
GameMaker's resources Sprites from a "game maker" program not top notch sprites but worth a look.
Molotov's sprites Free sprites, but watch out for ripped NES sprites in his links. Still a good resource.
3D Cafe Free 3D models,textures & sounds. Stonewashed Huge site linking to free sound resources.
If you know of some free resources not listed, why not send a mail about it:
Links 
